No one know what it is for. It has no impact on device. At first I tought its for tape types but nope.
Does it have a radio and does it record ? If so I would guess Interference Suppression System.. Only of relevance if you intend recording from AM, when the tape bias oscillator can interfere with some frequencies on the radio.
Wow. It has AM radio and recoding capabilities. But it doesn't hurt to not have that button right ? No AM radio is available anyway.
I guessed because most Boomboxes have a similar switch on the back, sometimes called "beat cut" or "beat cancel". https://www.vintage-radio.net/forum/showthread.php?t=71590 As I said previously it is only relevant when recording AM stations on certain frequencies. I wonder how many people ever needed to use it. The comment in the vintage radio thread about patchy or non existant FM is correct. In the UK Radio 1 didńt get its own FM frequency until 1987. When I bought a Pioneer car radio cassette with mechanical push button tuning in the mide 80s I chose one without FM because none of the stations I liked were on FM and that gave me more AM presets
I have a similar model with the same switch. Its for cutting noise when recording from AM. Although cutting noise when recording from AM on this model is the last of your worries!
What do you mean by that These models are little bit problematic I guess. If you mean that I am not alone :/ Unfortunately I had several issues with my walkman.
